Conventionally, it has been proposed to arrange an electronic circuit such as a memory or a logic circuit or the like, which is suitable for high speed operation, by combining a Josephson tunnel junction with other circuit elements to utilize a high speed switching capability of the Josephson tunnel junction.
By the way, as reported in, for example, "IEEE TRANSACTIONS ON ELECTRON DEVICES", Vol. ED-27, No.10, October 1980, pp 1857 to 1869, written by T. R. Gheewala, conventionally, there has been utilized, as the input signal for switching the Josephson tunnel junction, a current for generating a magnetic field for inhibiting the critical current of the Josephson tunnel junction or a current superimposed on the current from a current source wherein a sum of the currents exceeds the critical current of the Josephson tunnel junction.
However, with a superconducting circuit in which the foregoing magnetic field generating current is utilized as the input signal to switch the Josephson tunnel junction, since a magnetic circuit for magnetically coupling the magnetic field generating circuit and the Josephson tunnel junction is necessary, it has been difficult to miniaturize the circuit. On the other hand, in a superconducting circuit which switches the Josephson tunnel junction by using the foregoing superimposed current as the input signal, since the input signal is turned into an output signal superimposed with the current from a current source, it has become difficult to separate the input and the output.